Seasonal Dynamics of Photosynthetic Activity in Scots Pine Needles in the Central Region of European Russia

Conducting a comprehensive study of the photosynthesis aspects of the most common tree species will allow us to select the most promising species for afforestation and assess the contribution of the main forest-forming species to the absorption of carbon dioxide. This study investigates the seasonal dynamics of photosynthetic activity in Scots pine (Pinus sylvestris L.) needles in the central region of European Russia during the 2024 growing season. The research aimed to determine the dependence of photosynthesis intensity, transpiration, and stomatal conductance on meteorological conditions, such as temperature and irradiance. Measurements were carried out using a portable gas exchange system and meteorological station data, covering the growing season from April to September. The photosynthetic activity was found to exhibit a bimodal dynamic with peaks in June (20.8 μmol/m²/s) and September (18.0 μmol/m²/s), while the minimum value was observed in July during a drought period. The analysis of the results suggests a high adaptability of Scots pine to stressful conditions, attributed to the "drought memory" effect and the xeromorphic structure of the needles. The obtained data help to identify optimal conditions for reforestation activities and underscore the significant role of pine forests in the carbon balance of ecosystems.